Feed water by-pass seal for boiler circulating pumps



Oct. i4, 1941. H voRKAUF 2,259,361

FEED WATER BY-PASS SEAL FOR BOILER CIRCULATING PUMPS Filed oct, a, 195sl 32 E Wx ATTORNEYS Fatented @ch M, 'iil FEED' WATER Y-PAss SEALFon-nomia CIRCULATIN G PUMPS Heinrich'Vorkauf, Berlin, Germany, assiznorto La Mont Corporation, New York, N. Y., a corporation of New YorkAppuction october s, 193s, seria.: No. 233,95

In Germany October 9, 1937 1 Claim.

This invention relates to pumps which operate, on liquids raised torelatively high temperatures and usually also under relatively highpressures. The 'invention relates particularly to circulating pumps forforced circulation boilers which must withstand both the pressure andthe temperature of the boiler water.

' In the design and construction of pumps for forced circulationboilers, although these pumps are generally for the most part ofcomparatively simple construction, it is necessary to give particularattention to the stufling boxes, because of the high pressures andtemperatures of the water which they circulate. It has been found inpractice that injuries to the stufng box packings which occur in theoperation of such circulating pumps arise more from the hightemperatures than from the high pressures. For

this reason the stuffing boxes of hot liquid circulating pumps aregenerally cooled in some manner.

It has been proposed heretofore to create a sealing ring or circuit inthe stuiiing box with the aid of feed Water in such manner that the feedWater, under the same pressure or under a higher pressure than theboiler water, has 'a pressure drop in the stuing box through athrottling pass. One advantage of'this has been that a positive pressuredrop takes place in the stuiling box. It is, however, necessary, withthis ar. rangement, to cause the feed water which has been put underpressure to iiow back again into the feed water supply, thus makingspecial conduits necessary. Moreover, under this arrangement the feedpump has a higher loading. In accordancewith the present invention it isproposed to seal the stuffing box of a circulating pump by means of thecolder feed water and then to conduct this feed water to the circuit inwhich the boiler water is circulating under the boiler pressure.Advantageously, according to the present invention, the colder feedwater, after performing its function of sealing the stuffing box, isconducted into the suction conduit of the circulating pump, thus servingto shut off any tendency to steam formation in the suction conduit, animportant feature of the invention being an arrangement for thedischarge of the sealing water at the point where there is the mostmarked tendency to steam formation.

Other objects and important features of the invention will appear fromthe following descrip- Figure 1 is a vertical section through acirculating pump embodying the present invention, this figure showingthe provision for discharge of the feed water through an axial passagein the pump rotor shaft, and

Figure 2 is a vertical section through a similar pump showing anarrangement for discharging the sealing water through a special conduitentering the suction conduit to the pump outside the pump proper.

In Figure 1 of the drawing the pump rotor 2, mounted on the shaft 4, isshown as surrounded by a pump housing 6 having a boss 8 in which theshaft 4 has its bearings and in which the stufling box is located. Thestuiing box comprises packing IU and a removable combined gland andbearing I2 between which and the stationary bearing I4 the packing I0 isconfined. A removable cover I6 for the housing 6 is provided with aninlet or suctionopening I8 through which the water to be circulatedenters the pump.

The inner bearing I4 for the shaft 4 is provided with an annular passage20, adjacent to the shaft 4, through which the sealing water cancirculate. A tube 22,y extending through the boss 8 and intocommunication with the annular passage 20, provides for the introductionof the sealing water into the passage 2U, and a radial passage 24,communicating with an axial passage 26 in the shaft 4. which in turncommunicates with an approximately radial passage 28 through the hub ofthe rotor 2, provides for discharge of the sealing water into thesuction side of the pump and advantageously into those places in therotor where it will take part in the circulation, that is, at theentrance edge of the rotating blade as well as at the surrounding outerand inner annular surfaces of the rotor entrance, since at these placessteam formation first takes place because the friction between thesurrounding parts and the entering water effects a considerabledevelopment of heat.

Since the feed water will be under higher pressure than the circulatingwater and since naturally it is colder than the circulating water, whenthe feed water is used for the sealing water and 'is introduced into thepassage 20 through the tube 22 it not only will tend to cool the innerbearing I4 but by its sealing action it will prevent hot circulatingwater from traveling along this bearing in'to Contact with the stuffingbox packing ID. If, therefore, the temperature of the feed ,water issufficiently low, any other cooling ofthe stuillng box becomesunnecessary.

vIn the form f the. invention illustrated in Figure 2, the. sealingWater, instead-of being com ducted -away fromy the annular passage 20through the center of the shaft and through the rotor hub,. is carriedthrough an outside conduitv 30 into the suction conduit 32 leading tothe suction opening IB and is thus introduced. 'l

into the circulating water" on the suction side of the pump at a pointoutside the pump proper,v

s circulation boiler.

What is claimed as new is:

In aforced circulation boiler, a rotary pump for circulatingthe boilerwater, said pump comprising a, housing, a rotor, arotor shaft `and astufling box through which the shaft passes and in which it has its.bearings, and means, including a conduit from a source of feed watersupply,

(for introducing feed'water into the suction side .of said pump, saidconduit including an annular .passage in the pump housing, adjacent tothe rotor shaft and between the rotor and the stuffing box, and apassagethrough said shaft and througha part of said rotor, arranged todischarge the cold feed water substantially at the entrance edge of therotor blade.

. HEINRICH VORKAUF.

